Magnetic particle inspection is a non-destructive inspection technique used to detect flaws and defects in a ferromagnetic work piece. The work piece is magnetized using a magnetic inspection tool having two poles. Magnetic particles are sprayed or otherwise distributed across the work piece between the poles after the poles are placed against the work piece. The poles magnetize the work piece and cause the magnetic particles to align and gather within discontinuities along the surface of the work piece. The collection of the magnetic particles indicates a flaw that can be observed with the naked eye. Magnetic particles used in this process may be suspended in a fluid and sprayed on the work piece, and they may also be colored or fluorescent to improve visibility.
Most magnetic inspection tools include a pair of yokes with inspection magnets of opposite polarity. The yokes may include permanent magnetics or electromagnets for magnetizing the work piece. When pressed against the work piece, the yokes are attracted to its ferromagnetic material and induce a magnetic field through the work piece. One problem associated with this process arises when the work piece is located within a larger assembly and within tight confines. Each yoke must be located and affixed to the work piece before spreading the magnetic particles. Therefore, the size of the yoke may be a limiting factor on the ability to position a yoke on certain work pieces. Moreover, once the yoke is affixed to the work piece it is often difficult to remove it. Without sufficient clearance, it may be difficult to obtain the necessary leverage to remove the yoke once affixed to the work piece. Therefore releasing the yoke becomes an issue.
3D printing magnets are a relatively new process in which a plurality of magnetic sources are formed along a surface using a 3D printer to create an array of magnetic sources adjacent to one another. Each magnetic source is a pixel on the surface, each having its own polarity. The arrangement of polarities along the surface forms a magnetic pattern. That pattern can be matched with another printed magnet surface such that the two surfaces can attract or repel each other based on the orientation or rotational position of each. U.S. Patent Application Publication No. US 2012/0146752A1 (“the '752 publication”) to Fullerton discloses this 3D printing process.
While the '752 publication describes the 3D printing process generally, the present disclosure is directed to a magnetic particle inspection yoke having 3D printed magnetic members to address the one or more of the problems set forth above and in the prior art.